(a) If a fiduciary is required or elects to file a Fiduciary Amended Return, the Fiduciary shall file an OTC Form 513, write "Amended" on the face of the return and attach the following or attach an explanation if the following is not applicable:

1. (1) A copy of the Amended Federal Fiduciary Return, Form 1041, or Federal Form 1045.
2. (2) Proof that Internal Revenue Service has accepted the claim, such as a copy of the statement of adjustment, any correspondence from Internal Revenue Service, or a copy of the deposit slip of the Federal refund.
3. (3) Supporting documents for any adjustments to Federal Taxable Income to arrive at the Oklahoma Taxable Income.
4. (4) An explanation for the filing of a Fiduciary Amended Tax Return.